It is known in the art that polymerization of cyclic olefins provides unsaturated polymers which were disclosed to be useful, for example, as molded articles.
Polymerization of cyclic olefins via the so-called olefin metathesis reaction has been widely investigated since the first description appeared in 1960. Ivin has reviewed the work in this field (K. J. Ivin, "Cycloalkenes and Bicycloalkenes," Chapter 3 in K. J. Ivin, T. Saecjusa, eds. Ring-Opening Polymerization, Vol. 1, Elsevier: London, 1984, 121-183). Polymers produced via olefin metathesis of cyclic olefins still contain ##STR2## bonds, one for each monomer unit, and are thus distinct from polymers prepared using free radical or Ziegler-type catalysts, which produce saturated hydrocarbon polymers, and polymers prepared using ring-opening polymerizations of cationically sensitive monomers such as epoxides, in which heteroatoms are present and are involved in the polymerization chemistry by cleavage of a heteroatoms-carbon bond.
As this review and many patents teach, certain transition metal compounds can be used to catalyze olefin metathesis polymerization of cyclic olefins. Molybdenum (Mo), tungsten (W), and rhenium (Re), incorporated in either inorganic or organometallic compounds, have most often been employed. Catalysts based on transition metals from Periodic Groups 4, 5, 8, and 9 are also known. Heterogeneous catalysts have been taught, typically supported on alumina or silica. Most useful, however, are homogeneous or non-supported catalysts. The most frequently used homogeneous catalysts are based on high oxidation state compounds of Mo or W, such as WCl.sub.6, WOCl.sub.4 or MoCl.sub.6. Reaction products of these with phenolic compounds are also taught. Cocatalysts, usually containing an alkyl group bonded to a non-transition metal, are often used in combination with these, and cocatalysts are presumed to transfer at least one alkyl group to the transition metal. Most frequently, the cocatalysts are based on aluminum (Al), but alkyls of zinc, tin and other Group 14 metals, Group 1 metals (such as lithium), and Group 2 metals (such as magnesium) are also employed. Cocatalysts which are halogen-containing Lewis acids such as AlCl.sub.3 or sources of halide, either organic, organometallic, or inorganic, may be used in combination with the transition metal-containing compound, organic reagents may be added to slow the rate of polymerization; typically these contain Lewis-basic groups, usually containing nitrogen or oxygen. More specialized catalysts, usually organometallic compounds, are also known, and the most widely used of these are based on W or titanium (Ti). As is appreciated by those skilled in the art, all of these systems ate sensitive to water and air, some violently so, and accordingly the usual practice is to remove adventitious amounts of water and air or be limited to processes and compounds in which materials free of these impurities can be supplied to the catalyst. A robust W organometallic compound has recently been described (L. L. Blosch, K. Abbound, J. M. Boncella J. Amer. Chem. Soc. 1991, 113, 7066-7068), but it requires the use of water-sensitive AlCl.sub.3 as cocatalyst to be active as an olefin metathesis polymerization catalyst. Certain of the above catalysts and cocatalysts may have other disadvantages as well. For example, use of organic sources of halide such as CCl.sub.4 is undesirable because such compounds are carcinogenic. Use of alkyltin compounds is undesirable because such materials are known to be toxic to certain organisms and harmful to humans, and they are heavily regulated by such agencies as the U.S. Environmental Protection Agency, particularly with respect to use and disposal. Still other systems require the use of solvents, making them unsuitable for solvent-free processes; solvent-free processes are desirable because they provide environmental and cost advantages.
A smaller body of background art teaches the use of Periodic Groups 8 and 9 transition metal compounds for olefin metathesis, especially compounds containing ruthenium (Ru), osmium (Os), and iridium (Ir). U.S. Pat. Nos. 3,367,924 and 3,435,016 disclose use of Ir halides and R. E. Rinehart and H. P. Smith in J. Polym. Sci., B (Polymer Letters) 1965, 3, pp 1049-1052 disclose Ru halides as catalysts for olefin metathesis polymerization of cyclic olefins in inert and protic solvents, including water. F. W. Michelotti and W. P. Keaveney in J. Polym. Sci: A 1965, 3, pp 895-905 describe hydrated trichlorides of Ru, Ir and Os as polymerization catalysts in alcohol solvents. F. W. Michelotti and J. H. Carter in Polymer Preprints 1965, 6, pp 224-233 describe the use of IrCl.sub.3.3H.sub.2 O under nitrogen atmosphere to produce polymer in varying yields from functional group-containing norbornenes. Grubbs in U.S. Pat. Nos. 4,883,851, 4,945,144, and 4,945,141 teach Ru and Os compounds as catalysts for polymerization of 7 -oxanorbornenes. It is believed that cocatalysts have not been described for Ru, Os, or Ir-containing olefin metathesis polymerization catalysts.
Certain olefin metathesis polymerization cocatalysts which are not sensitive to air or water have been taught; however, they are used in combination with air or water sensitive transition metal compounds, so that the reaction mixture still must be scrubbed of and protected from water or air or both. U.S. Pat. No. 4,490,512 and K. Weiss and R. Goller in J. Mol. Catal. 1986, 36, 39-45 disclose ring-opening metathesis of cycloolefins (e.g., cyclopentene or cycloheptene) in the presence of WCl.sub.6 and a 1-alkyne to give, for example, poly-1-pentenylene or poly-1-heptenylene, respectively. U.S. Pat. No. 4,334,048 describes the use of acetylenes with air-sensitive W-carbene compound under inert conditions to give low yields of polymer.
Cocatalysts containing silyl hydride ##STR3## are used with the reaction products obtained from air-sensitive tungsten halide plus a phenolic compound as disclosed in U.S. Pat. No. 4,994,426 for polymerization of substituted norbornenes. A combination of a tungsten compound and a tin-hydride has also been employed in U.S. Pat. Nos. 5,019,544 and 4,729,976. Z. Foltynowicz, B. Marciniec, and C. Pietraszuk in J. Mol. Catal. 1991, 65, 113-125 describe reaction of vinyltriethoxysilane as reagent with alkenes in the presence of RuCl.sub.3 and RuCl.sub.2 (PPh.sub.3).sub.3 (wherein Ph=phenyl), although they do not teach polymerization of cyclic olefins.
Oxidative cocatalysts have been used in various circumstances. For example, oxygen is described as having varying effects upon on olefin metathesis polymerization catalysts by V. A. Bhanu and K. Kishore in Chem. Rev. 1991, 91 (2), pp 99-117 (see especially 112-113). In particular, apparent beneficial effects of oxygen (O.sub.2) upon Ru-containing compound catalyzed norbornene polymerization reactions are attributed to initial epoxide formation by K. J. Ivin, B. S. R. Reddy, and J. J. Rooney in J. Chem. Soc., Chem. Comm. 1981, 1062-1064.
In non-analogous art, the effect of [Cp.sub.2 Fe].sup.+ PF.sub.6.sup.- on W-containing catalysts for alkyne polymerization has been described by M.-H. Desbois and D. Astruc in New J. Chem. 1989, 13, 595-600. Photoassisted W(CO).sub.6 catalysts for acetylene polymerization have been disclosed by S.J. Landon, P.M. Shulman and G.L. Geoffroy, in J. Am. Chem. Soc. 1985 107, 6739-6740.
Heteroatom-containing alkene reagents have been disclosed by C. T. Thu, T. Bastelberger, and H. Hocker in Makromol. Chem., Rapid Commun. 1981, 2, pp 383-386. This reference describes the polymerization of a cyclic vinyl ether in the presence of a chromium-carbene compound under nitrogen atmosphere.
All of the transition metal catalyst and cocatalyst systems described in the background art are deficient in that they are either moisture sensitive and/or air sensitive, or they do not teach polymerization of cyclic olefins via olefin metathesis.
Methods employing photolysis for metathesis of olefinic compounds using W(CO).sub.6 in the presence of CCl.sub.4 have been disclosed by A. Agapiou and E. McNelis in J. Chem. Soc., Chem. Comm. 1975, 187, and by C. Tanielian, R. Kieffer, and A. Harfouch in Tetrahedron Lett. 1977, 52, 4589-4592. P. Krausz, F. Garnier, and J. Dubois in J. Organomet. Chem., 1978, 146, 125-134 disclose photoassisted olefin metathesis of trans-2-pentene in the presence Of W(CO).sub.6 /CCl.sub.4 to provide a mixture of 2-butene and 3-hexene. No polymers are taught. Certain tungsten-containing compounds and Lewis acid cocatalysts such as AlCl.sub.3 or ZrCl.sub.4 have also been disclosed by T. Szymanska-Buzar and J.J. Ziolkowski in J. Mol. Cat., 1987, 43, 161-170, for metathesis of linear olefins. No polymerization is taught. All of these systems are deficient in that they are sensitive to air or water, employ halogen-containing cocatalysts, or do not teach the polymerization via olefin metathesis of cyclic olefins.